I am looking for way to draw and write comments in VScode on top of my code. Like how we can in Adobe reader.
See Menu item "Edit"/"Toggle Line Comment" or "Edit/Toggle Block Comment". There you can also find the key combinations to comment or uncomment a line or a block.
How to put comments into a code file depends on the type of file, which is often governed by the filename extension (.e.g.
.sh), or by the first line of the file. If the first line starts with
#! (these two bytes of the file are called "shebang") it says "following these these two characters, there is a call to a program to run this file".
If you want to use a documentation generator such as javadoc, phpdoc, jsdoc ... this is often the task of VSCode extensions. No general advice is possible, as far as I know.